1. Field of the Invention
The invention relates to an article pickup device that uses a robot to pick up a great number of articles such as workpieces that are placed in a container, a basket, or on a pallet.
2. Description of the Related Art
It is a known practice to utilize robots for sequentially picking up a lot of articles (such as workpieces) stored in a container or basket or placed on a pallet at factories and the like. In such a case, articles are very often placed in bulk without fixed positions for each sort of article. Thus, as is disclosed in Japanese Patent Application Laid-Open No. 2001-179669, a technique is proposed that detects the position/attitude of articles by means of a visual sensor and operates a robot to pick up the articles based on the detection.
However, most of prior arts employing visual sensors cover the range in which a lot of articles exist (the entire area of a container, pallet, basket where the articles are stored, for example) with the field of view of a single camera (the imaging means of a visual sensor). As a matter of course, under such a condition (covering the entire area), articles generally tend to be very small relative to the size of the field of view, and thus reliability and accuracy of article detection (including discrimination of front/back and sorts) are likely to be insufficient.
To compensate for this drawback, in some cases a camera is additionally provided for ensuring reliability and accuracy in addition to the camera that covers the presence range for articles (such as a container, pallet, and basket) in its entirety. This practice, however, poses a problem that it involves two cameras and the system becomes more complicated accordingly.